Combined magnetizer and demagnetizer



C. D. SMITH COMBINED MAGNETIZER AND DEMAGNETIZER Sept. 16, 1969 3 Sheets-Sheet 2 Filed April 7, 1967 FIG- IrranviY-f Sept. 16, 1969 c, 0. SMITH 3,467,926

COMBINED MAGNETIZER AND DEMAGNETIZER Filed April 7, 1967 3 Sheets-Sheet 3 U T H9 wri/vro? C" a ya .22 SM/ 7w ITTOP/VIYJ United States Patent F 3,467,926 COMBINED MAGNETIZER AND DEMAGNETIZER Cloyd D. Smith, 13805 Rancheros Drive, Reno, Nev. 89502 Filed Apr. 7, 1967, Ser. No. 629,256 Int. Cl. H01f 13/00, 7/02 US. Cl. 335284 4 Claims ABSTRACT OF THE DISCLOSURE A combined magnetizer and demagnetizer constructed with a strong permanent magnet having a pair of opposed, parallel, major surfaces, each carrying an opposite polarity, and a ferromagnetic plate substantially coextensive with and mounted on one of the major surfaces of the magnet.

The invention relates to improvements in devices for magnetizing and demagnetizing ferrous members, such as screwdrivers.

It is frequently desirable to induce magnetism in a hand tool, such as a screwdriver or a tack hammer in order to start a screw or a nail. Heretofore, it has been customary to use either a large bar magnet or an electromagnet to effect this result.

It is also often necessary to demagnetize an object. For example, watchmakers ordinarily wish only to use screwdrivers, probes and other similar tools of their trade which are entirely free from any magnetism.

Heretofore, demagnetization has, for the most part, been effected by subjecting a tool possessing some degree of magnetism to a powerful alternating field.

Another, although less favored, procedure for removing magnetism includes heating the magnetic item to a high temperature; or jarring it repeatedly.

The foregoing operations involve the use of moderately complex apparatus, a source of energy, and the expenditure of considerable time and effort.

It is therefore an object of the invention to provide a combined magnetizing and demagnetizing device which is small in size, yet is entirely self-contained, durable, inexpensive and reliable.

It is another object of the invention to provide a magnetic device which quickly effects either magnetization or demagnetization in dependence upon its manner of use. g

It is a further object of the invention to provide a mag netic device which has no moving parts to get out of order, and in which the correct manner of use can readily be learned.

It is another object of the invention to rovide a generally improved combined magnetizer and demagnetizer.

Other objects, together with the foregoing, are attained in the embodiments described in the following description and illustrated in the accompanying drawings in which:

FIGURE 1 is a top plan view of one form of the device showing, in broken line, a portion of the shank of a screwdriver being wiped across the magnet to induce magnetism into the screwdriver;

FIGURE 2 is a side elevational view, portions being broken away to reveal the underlying structure;

FIGURE 3 is a bottom plan view;

FIGURE 4 is a fragmentary transverse sectional view, to an enlarged scale, showing a portion of the shank of a screwdriver undergoing demagnetization, the plane being indicated by the line 4-4 in FIGURE 3;

FIGURE 5 is a prespective view of a modified form of the device, showing in broken'line the position of a screwdriver being magnetized;

FIGURE 6 is a median, vertical, longitudinal sectional view of the FIGURE 5 form of device;

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FIGURE 7 is a transverse sectional view, the plane of the section being indicated by the line 77 in FIGURE 5;

FIGURE 8 is an idealized sectional View to an enlarged scale of a magnet, showing a screwdriver being demagnetized; and,

FIGURE 9 is a side elevation of another modification.

While the combined magnetizer and demagnetizer of the invention is susceptible of numerous hysical embodiments, depending upon the environment and requirements of use, substantial numbers of the herein shown and described embodiment have been made and tested, and all have performed in an eminently satisfactory manner.

The form of the invention illustrated in FIGURES 1 through 4 is, for convenience, designated as the paddle form and bears the general reference numeral 12.

A handle 13 having a size and configuration lending it self to convenient grasping by one hand is secured, as by rivets 14, to an elongated sheet metal plate 16 projecting beyond the handle and terminating, for the sake of appearance and protection, in a rounded tip 17. An opening 18 in the base end of the handle allows the device to be suspended from a nail in the wall or bench for ease and compactness of storage. I

A pair of lateral flanges 19 on the plate turns at right angles to the plate 16 and at least partially covers the lateral edge surfaces 21 of a strong permanent magnet 22.

The magnet 22 is secured to the underlying sheet metal plate 16 and to the upstanding flanges 19 by an appropriate adhesive.

The magnet 22 is a parallelepiped in configuration, and in addition to the opposite pair of narrow lateral edge surfaces 21, also includes an opposite pair of large side surfaces, namely an outer, exposed, side surface 23 and an inner side surface 24 (see FIGURE 2).

The major side surfaces 23 and 24, and the minor edge surfaces 21 are at right angles, their intersection aflording an exposed pair of corner lines 26 and an interior pair of corner lines 27 (see FIGURE 4). The interior corner lines 27 are enclosed by the flanges 19, and the right angled flanges 19, in turn, carry an exposed pair of corner lines 31.

At its opposite fore and after ends, the magnet 22 terminates to form a pair of transverse end surfaces 36.

In order to magnetize the ferromagnetic shank 41 (of a screwdriver 42, for example), the paddle handle 13 is grasped in one hand with the face 23 up. Then the screwdriver handle 42 is taken with the other hand and the shank 41 placed on the upper, or exposed major surface 23 of the magnet, as shown in FIGURE 1. The shank 41 is thereupon wiped across the surface 23 in the direction indicated by the arrow 43. If desired, the tool 42 can be lifted from the surface at the end of the stroke and the cycle repeated to increase the induced magnetism.

In order to demagnetize the shank, on the other hand, quite a different procedure is followed. When demagnetizing, the paddle is held with the plate 16 side facing upwardly as in FIGURE 3. The screwdriver is then placed with the butt end of the metal shank 41 engaging one or the other of the flange corners 31 as in FIGURE 4. While maintaining the shank at an angle, the shank is drawn sharply downwardly and toward the right, as in FIGURE 4, in the direction of the arrow 46. At the conclusion of but one stroke, demagnetization is effected.

It has been discovered, as a matter of considerable interest, that demagnetization is most efficiently achieved by first magnetizing the shank prior to demagnetizing.

In other Words, when a tool to be demagnetized, such as a screwdriver, possesses even a small degree of residual magnetism it has been found preferable first to subject it to the magnetizing procedure stated above, followed by wiping it across a flange corner in the .demagnetizing operation, as described.

The precise reason why this phenomenon occurs is not known. It would seem, however, that by first aligning substantially all of the magnetic particles within the shank, by the magnetizing step, the subsequent step of demagnetizing is more effective in that a greater number of particles become effectively disoriented as a result of the demagnetizing operation.

In this connection, it is believed appropriate to discuss briefly what is believed to be a possible explanation of the results afforded by the present invention.

The magnetizing step, or operation, is perhaps best explained by the classical molecular theory first advanced by Weber (Wilhelm Edward, 1804-1891, a German physicist who, for most of his life, occupied the chair of physics at Gottingen). Under the Weber theory, each of the molecules in the screwdriver shank is assumed to be a very small magnetic particle with its own Northpole and South-pole. When no magnetizing force is being applied, these small magnets are arranged in a haphazard manner so that the various molecular N- and S-poles all neutralize one another, and no external magnetic effect, or field, is produced. I

On the application of a magnetizing force, however, the small magnets tend to arrange themselves so that their axes are parallel and their N-poles are all pointing in the same general direction as the magnetizing force.

A more recent theory of magnetism that is perhaps more adequate than the classical molecular theor is the domain theory. Most simplified, this theory may be stated as follows:

In magnetic substances the atomic magnets, produced by the movement of the planetary electrons around the nucleus, have a strong tendency to line up together in groups of from to 10 atoms regardless of and without the influence of any external magnetic field.

These groups of atoms having their poles oriented in the same direction are called domains. Therefore, throughout each domain an intense magnetic field is produced.

These individual fields are, however, normally in a miscellaneous arrangement so that no external field is apparent when the substance, such as the screwdriver shank, is in an unmagnetized condition.

Each tiny domain (10 of them may be contained in one cubic millimeter) is always magnetized to saturation, and the addition of an external magnetic field does not increase the inherent magnetism of the individual domains as seen from a microscopic point of view.

However, the addition of an external magnetic field is effective to align the individual domains with the external field, such as by wiping the screwdriver shank 41 across the magnet 22.

After alignment of a very large number of domains occurs, the substance as a whole exerts an external magnetic field, i.e. it is itself magnetized.

As previously mentioned, demagnetization has historically been achieved in a variety of ways.

First, a magnetic object, allowed to remain for a long period of time disoriented with respect to the earths magnetic field, will, in due course, lose its magnetism; i.e. its individual molecular magnets or its domains will, in time, re-assume a random arrangement.

Jarring and heating the magnetized object are other methods effective to yield reorientation of the particles into haphazard patterns.

A powerful alternating current field imposed upon a magnetized article has also long been used, for example, to demagnetize tools, watches, etc. The rapidly expanding and collapsing field produced by a conductor coil carrying AC. has heretofore been widely used despite the disadvantages of requiring an energy source, wires and special equipment.

Using the present device, however, a magnetized object, such as a screwdriver, is effectively demagnetized,

4 as described above without any need to resort to the expedients mentioned.

Reference is now had to the block form of device shown in FIGURES 5-7.

A parallelepiped 51, such as a block, of non-magnetic material, carries a pair of rounded end portions 52 connected by an elongated central vertical web 53 pierced longitudinally by a horizontal through-bore 54, and, vertically, by an intersecting aperture 56 (see FIGURES 6 and 7).

The circular cross-section through-bore 54 lends itself to use in magnetizing elongated objects, such as screwdriver shanks 55, or probes, or rods, whereas the longitudinally distended vertical aperture 56 is especially useful in magnetizing objects having some width, such as a small end wrench or a small crescent wrench.

An opposed pair of recesses 57 formed in the sides of the block snugly receives a corresponding pair of strong permanent magnets 61.

Serving to confine the magnets 61 in the recesses 57 is a pair of protective, paramagnetic plates 62 having chisel-shaped ends 63 receivable in corresponding V- shaped vertical grooves 64 in the end caps 52. A strong adhesive is often used to secure the magnets and plates to the mutually engaging walls and grooves of the block member 51.

The magnets 61 are of the same kind as previously described in connection with the FIGURES 1-4 form of device, and each includes a pair of major side surfaces 66, a pair of minor edge surfaces 67 and a pair of end surfaces 68. One major surface is an N-pole; the other, an S-pole.

The plates 62 differ somewhat, however, from the earlier described plates 16 of the FIGURES 1-4 form of device.

The plates 62 are not flanged. Instead, they are substantially planar and are substantially coextensive with the side surfaces 66 of the magnets. In fact, it has been found by exhaustive experimentation, that the plates 62 serve their demagnetization function most efficiently when their width (shown vertically in FIGURES 5 and 7) is precisely equal to the vertical width of the magnets 61.

In order to magnetize an object 55, such as a screwdriver, the screwdriver shank is inserted through the bore 54 to the hilt (see FIGURE 6), then is withdrawn.

If desired, the aperture 56 can be used rather than the bore 54. In either case, the slight thickness of the web material (e.g., plastic) does not materially interfere with magnetization.

One cycle, i.e. insertion and withdrawal, is ordinarily sufficient to induce a strong permanent magnetism even in a hard steel object.

Parenthetically, it is to be noted that a soft iron or a soft steel object (such as a brad or nail) is more readily magnetized, but retains only a very small portion of the magnetism initially imparted to it. A hard steel resists being magnetized, but upon being magnetized, is permanent.

In connection with the magnetization step, it is believed that the intense opposed field existing in the central portion of the block between the two like pole pieces is helpful in overcoming the low permeability of the hard steel of the object, and thereby effectively induces a permanent magnetism therein even though only one cycle of magnetization is used.

In order to demagnetize the object (the screwdriver shank 55, for example) the butt end of the shank is placed against the outer corner 71 of the plate 62 (or horizontally across the top or bottom) and sharply wiped. At the conclusion of the stroke, demagnetization is effected.

Reference is now had to FIGURE 8 to help explain what is believed to happen to the aligned, magnetic molecules or domains as the shank 55 is progressively swept over the plate 62.

It has been found, incidentally, as in the previously described form of device that best results are obtained in demagnetizing by first subjecting the object to the above described magnetizing step, then following this with the de'magnetizing step.

FIGURE 8 illustrates in idealized form a magnet 81 of the type used herein, namely, a magnet having a pair of opposedmajor side surfaces 82 (N-pole) and 83 (S- pole) as well as a pair of minor edge surfaces 84.

For the purposes of FIGURE 8, a protective, paramagnetic plate is not shown.

It has been found, as a matter of interest, that the plates 16 (and 62) not only protect the adjacent magnets 22 and 61, respectively, as wiping is effected, but they also apparently helpfully serve to distort the magnetic field in accordance with the well know law of the magnetic field to the effect that the magnetic field" always tends to conform itself so that the maximum amount of flux is attained.

In the presence of ferromagnetic material such as the plates 16 and 62, in other words, the force lines are drawn toward and into the plates and serve greatly to intensify the field immediately adjacent the portion upon which the screwdriver is wiped.

Shown being moved along the corner 86 in FIGURE 8 is a ferromagnetic rod 87 previously rnagnetized'so that the molecules 88, or domains, or particles, or dipoles are longitudinally aligned, as appears in the upper left hand end of the rod.

Arbitrarily, attention is directed to one individual dipole 88 assumed to lie on the axis 89 of the rod, the dipole being oriented so that its N-pole (small'hollow circle) is at the upper end, and its S-pole (small filledin circle) is at the lower end.

The uppermost dipole 88 is further assumed to take the successive lower positions shown as the rod is swept downwardly in the direction of the arrow91, as in a motion picture sequence.

The broken lines 92 depict, in well-known manner, the imaginary lines of force existing in the magnetic field 93 exerted by the strong permanent magnet 81.

As the rod 87 moves downwardly, the axially aligned particle 88 encounters the force line 92a, tending to reorient the particle, tangentto the force line, into the attitude, as at 88a, with the S-pole of he particle facmg toward the north pole 82 of the magnet 81.

As will be appreciated, the force exerted on the particle will vary inversely in power with the distance. Thus, as the particle sweeps through the vicinity of the corner 86, a more intense effort is applied, the particle being severely re-oriented, even possibly assuming the reverse orientation indicated at 88 Thereafter, but with weaker effect, as the subsequent force lines are out, still different postures are assumed, as shown in stylized fashlon 1n FIGURE 8.

The total effect on all of the various particles located throughout the rod is to return them to a haphazard arrangement wherein no external magnetic field is provided. The rod, in short, is demagnetized.

Reference is now had to another modification, as shown in FIGURE 9. This modification 112 resembles in many respects, the paddle form of device 12 illustrated in FIGURES 1-4, like reference numerals being applied, where appropriate.

T-he FIGURE 9 modification differs, however, in that the upper, exposed side surface 23 of the magnet 22, is covered by a sheet 116 of non-ferrous material, such as aluminum.

The lateral margins of the aluminum sheet 116 are bent downwardly, at right angles, to form a pair of flanges 119 abutting the corresponding upstanding flanges 19 formed of ferrous material. The end 117 of the aluminum sheet 116 projects forwardly and corresponds to the forward projection 17 of the ferrous plate 16.

The FIGURE 9 form of device affords an especially interesting, unexpected and useful result both as to magnetizing and demagnetizing a tool, such as a screwdriver shank 14.

Magnetization is effected in essentially the same manner as previously explained in connection with the FIGURES 14 form of device. This is to say, the screwdriver shank 141 is placed horizontally on the upper surface of the non-ferrous sheet 116 transversely with respect to the magnet 22, as in FIGURE 1, and is wiped across the sheet from hilt to tip of the screwdriver shank.

Demagnetization, on the other hand, is achieved by quite a different procedure.

This demagnetization procedure is as follows. The screwdriver shank 141 is first positioned in a horizontal, attitude, as appears in full line in FIGURE 9, with the shank located about inch above the surface 121 of the non-ferrous sheet 116, the screwdriver being axially positioned approximately in the position shown in broken line in FIGURE 1.

The screwdriver is thereupon vertically lowered in the direction of the arrow 142 (see FIGURE 9), until the shank 141 horizontally touches or engages the horizontal upper surface 121 of the non-ferrous sheet 116, as indicated in broken line in FIGURE 9.

The shank 141 is touched only instaneously to the sheet, and is thereupon returned to approximately the upper location shown in full line in FIGURE 9.

Then, the screwdriver is shifted axially toward the observer, ie in the direction of the arrow 43 in FIGURE 1, by an amount approximately equal to the transverse width of the magnet 22; and the cycle of lowering, touching and lifting the shank is repeated.

Where the screwdriver shank 141 is about equal in length to twice the transverse width of the magnet 22,

only two cycles are necessary; where, however, the screwdriver shank is approximately equal to three times the transverse width of the magnet 22, three cycles are preferable.

The effect of lowering the previously magnetized shank against the upper surfac of the non-magnetic sheet 116 covering the upper surface 23 of the magnet 22, followed by vertically lifting the shank, shifting the shank axially, and repeating this cycle, in dependence upon the general relationship between the shank length and the magnet width, has been found to be of unusual effectiveness in re-arranging the magnetic molecules or domains of the tool substance so as to provide thorough demagnetization.

The accompanying drawings, and the foregoing description illustrate the relative dimensions, configurations and manner of use of three successfully tested forms of the device. However, it will be appreciated that still other variant forms and modes of operation can be utilized while still remaining within the scope of the subtended claims.

What is claimed is:

1. A magnetic device comprising:

(a) a parallelepiped of permanent magnetic material having a pair of opposite side surfaces and a pair of opposite edge surfaces normal to said side surf-aces to form right angular corners, said material being magnetized to afford a north pole on one of said side surfaces and a south pole on the other of said side surfaces;

(b) a metallic plate of ferrous material substantially coextensive in size with one of said side surfaces, said plate being mounted on said one of said side surfaces in face to face engagement therewith; and,

(c) a block of non-magnetic plastic material having a through-bore formed therein and an aperture extending through said block at right angles to said through-bore and intersecting the same, and wherein a pair of said magnetic parallelipipeds is mounted on opposite sides of said block adjacent 7 8 said through-bore with said plates facing away from I at right angles to overlie at least a portion of said said through-bore. opposite edge surfaces;

2. A device as in claim 1 wherein each of said parallel- (c) a second plate substantially coextensive in size epipeds is identical in size with the other and terminates and in face-to-face engagement with the opposite of in a pair of opposite end surfaces at right angles to said 5 said major side surfaces and including a pair of side surfaces and said edge surfaces. flanges bent at right angles to overlie at least 3. A device as in claim 2 wherein said parallelepipeds a portion of said opposite edge surfaces; and, and said plates are elongated and are of the same (d) an elongated handle mounted on at least one of idth, said plates and extending in a direction normal to and 4. A combined magnetizing and demagnetizing device 10 away from said end surfaces. comprising:

(a) a parallelepiped of permanent magnetic material References Cited having a pair of major opposite side surfaces, a pair UNI STATES PATENTS of minor opposite edge surfaces and a pair of minor 2 opposite end surfaces, each of said pairs of surfaces 15 33?;3; 9/1959 Korodl 335-285 XR being at right angles relative to the others, said mate- 3 331 043 gjggg a1 rial being magnetized to afford a north pole on one 1. 3 54 10/1967 Miyata 335 306 XR of said major side surfaces, and a south pole on the other one of said major side surfaces; G. HARRIS, Primary Examiner (b) a first plate substantially coextensive in size and 20 in face to face engagement with one of said major side surfaces and including a pair of flanges bent 335 306 

